The present invention relates generally to the laboratory preparation of orthodontic devices and more particularly to the fitting of brackets upon teeth to be orthodontically treated. Furthermore, the invention involves the utilization of positive jaw models in effecting the proper adjustment and positioning of the brackets. The invention also involves the utilization of negative molds of tooth and jaw structures which may be prepared from the positive jaw models and which may be utilized to apply the orthodontic brackets onto the teeth to be treated by means of appropriate dental cement or other similar adhesive.
A known prior art procedure which is related to the present invention is disclosed in a trade publication entitled "Informationen auf Orthodontie und Kieferothopadie", Jan. 1973 issue, pp. 45 ff. A very important factor in the practice of procedures of this type is the precise and correct placement of brackets upon teeth of a positive jaw model which is utilized in the bracket-fitting procedure. This requirement exists as well in formerly known procedures wherein the fitting is formed without a model because it effects the precise and proper fitting of the brackets to the teeth which are to be ultimately treated. The placement and positioning of the brackets upon the teeth must be carefully performed and the procedures must be compatible with the implements which are utilized and with the overall apparatus by which such procedures are performed. If adjustment is to be accomplished with so-called tension arcs, wherein an arc wire is elastically deformed to conform with the orientation of an uneven row of teeth, the success of the treatment procedure depends particularly upon the proper placement and angular positioning of the orthodontic brackets upon each individual tooth. Once a bracket has been fitted upon a respective tooth, its position cannot be changed until the completion of the treatment process. Therefore, if tensioned arcs are to be used, the brackets must be adjusted in such a way that the arc which is finally utilized, which may have a square cross-sectional configuration, will extend through corresponding square slots of each of the brackets without deviation or twist. Thus, the stretching of the tensioned arcs must occur in an appropriate manner and the overall system must accommodate the use of different tensioned arcs of increasingly heavier gauge which are periodically replaced after initiation of the treatment process.
Usually, the procedures which are involved require that tensioned arcs having a generally rounded cross-sectional configuration be used initially and that replacement of the arcs be effected until, finally, a heavier gauge arc of generally square cross-sections is used. In order to comply with these requirements in a manner which achieves placement of the brackets upon the teeth to be treated as precisely as possible, it has hitherto been known to use a plurality of brackets of differing designs with regard to the angular positioning of the bracket slots and bracket feet, due to the fact that the bracket slots must conform on the adjusted denture to an ideal course or path not only with regard to the horizontal course of the arc, but also with regard to their vertical surfaces. This occurs without regard to the fact that the teeth may be of different volumes. The ideal course of the tensioned arc results from a line which may be drawn through the exit points of the imaginary tooth axes on the crowns of the teeth of a sound denture. However, in view of the fact that individual teeth project with marked differences from this ideal tooth arc line, the feet of the brackets must present a correspondingly different spacing from the brackets slots if the slots are to extend parallel to the ideal line of the tooth arc.
Despite the fact that scientific research has made commercially available an assortment of brackets which are designed to correspond to the characteristics of individual teeth, the orthodontic practitioner must nevertheless encounter the difficult task of properly evaluating individual teeth in order to fit the appropriate bracket in each given case with a correct positioning on the tooth. A projected view of the imaginary axis of the teeth plays an essential role within the context of an assessment of such imaginary axis. This relates to the corrected overall position of the still uncorrected dentures. Even though the procedures described above are facilitated to some extent by the fact that positive jaw models may be utilized, problems will nevertheless occur just as the case where brackets are directly fitted to the teeth in the mouth.
Accordingly, the present invention is directed toward substantially facilitating the fitting of brackets to the teeth of a positive jaw model. The invention obviates the need for complicated measurements and calculations as well as the selection of multiple brackets of different shapes. Furthermore, the invention is directed toward mechanization or standardization of the laboratory preparation and fitting of the brackets to the teeth in such a manner that the work may be performed as a more or less routine procedure even by personnel which do not have highly specialized training in the field.